求问关于Android获取网络图片的 ，我写的返回值为空，求帮助

Question

package com.example.internetpicture;

import java.io.IOException;
import java.net.URL;

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.Menu;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity {

private Bitmap mBitmap;
private ImageView img;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
RefreshDB();
img = (ImageView)findViewById(R.id.Img);
img.setImageBitmap(RefreshDB());
}

private ImageView findById() {
// TODO Auto-generated method stub
return null;
}

public Bitmap RefreshDB()
{
try
{
mBitmap = getImg("http://t11.baidu.com/it/u=1693178669,940960457&fm=21&gp=0.jpg");
return mBitmap;
}catch(Exception e)
{
Toast toast = Toast.makeText(getApplicationContext(), "图片转换出错", Toast.LENGTH_LONG);
return null;
}
}
public static Bitmap getImg(String url) throws Exception{
try
{
URL Url = new URL(url);
String reponseCode = Url.openConnection().getHeaderField(0);
if(reponseCode.indexOf("200") < 0)
throw new Exception("图片文件不存在，错误代码：" + reponseCode);
return BitmapFactory.decodeStream(Url.openStream());
}catch(IOException e)
{
return null;
}
}
}

Answer 1

http://t11.baidu.com/it/u=1693178669,940960457&fm=21&gp=0.jpg
直接在地址栏输入这个地址，返回403 Forbidden，图片问题，这是一个问题，第二个问题，android4.0后联网操作就不允许在主线程操作了，所以你需要另外开一个子线程下载图片。